ticdc unified sorter 几个疑问

今天又遇到了这个问题

[
  {
    "id": "tidboom-task",
    "summary": {
      "state": "normal",
      "tso": 426470011965276162,
      "checkpoint": "2021-07-21 15:53:08.515",
      "error": {
        "addr": "192.168.149.156:8302",
        "code": "CDC:ErrProcessorUnknown",
        "message": "[CDC:ErrMySQLTxnError]Error 1105: runtime error: index out of range [7] with length 7"
      }
    }
  }
]

日志里有如下信息

[2021/07/21 17:29:01.591 +08:00] [WARN] [mysql.go:903] ["failed to rollback txn"] [error="Error 1105: runtime error: index out of range [7] with length 7"]
[2021/07/21 17:29:01.591 +08:00] [WARN] [mysql.go:882] ["execute DMLs with error, retry later"] [error="[CDC:ErrMySQLTxnError]Error 1105: runtime error: index out of range [7] with length 7"] [errorVerbose="[CDC:ErrMySQLTxnError]Error 1105: runtime error: index out of range [7] with length 7\
github.com/pingcap/errors.AddStack\
\tgithub.com/pingcap/errors@v0.11.5-0.20201126102027-b0a155152ca3/errors.go:174\
github.com/pingcap/errors.(*Error).GenWithStackByCause\
\tgithub.com/pingcap/errors@v0.11.5-0.20201126102027-b0a155152ca3/normalize.go:279\
github.com/pingcap/ticdc/pkg/errors.WrapError\
\tgithub.com/pingcap/ticdc/pkg/errors/helper.go:28\
github.com/pingcap/ticdc/cdc/sink.(*mysqlSink).execDMLWithMaxRetries.func2.3\
\tgithub.com/pingcap/ticdc/cdc/sink/mysql.go:905\
github.com/pingcap/ticdc/cdc/sink.(*Statistics).RecordBatchExecution\
\tgithub.com/pingcap/ticdc/cdc/sink/statistics.go:99\
github.com/pingcap/ticdc/cdc/sink.(*mysqlSink).execDMLWithMaxRetries.func2\
\tgithub.com/pingcap/ticdc/cdc/sink/mysql.go:893\
github.com/pingcap/ticdc/pkg/retry.Run.func1\
\tgithub.com/pingcap/ticdc/pkg/retry/retry.go:32\
github.com/cenkalti/backoff.RetryNotify\
\tgithub.com/cenkalti/backoff@v2.2.1+incompatible/retry.go:37\
github.com/cenkalti/backoff.Retry\
\tgithub.com/cenkalti/backoff@v2.2.1+incompatible/retry.go:24\
github.com/pingcap/ticdc/pkg/retry.Run\
\tgithub.com/pingcap/ticdc/pkg/retry/retry.go:31\
github.com/pingcap/ticdc/cdc/sink.(*mysqlSink).execDMLWithMaxRetries\
\tgithub.com/pingcap/ticdc/cdc/sink/mysql.go:885\
github.com/pingcap/ticdc/cdc/sink.(*mysqlSink).execDMLs\
\tgithub.com/pingcap/ticdc/cdc/sink/mysql.go:1044\
github.com/pingcap/ticdc/cdc/sink.(*mysqlSinkWorker).run.func3\
\tgithub.com/pingcap/ticdc/cdc/sink/mysql.go:799\
github.com/pingcap/ticdc/cdc/sink.(*mysqlSinkWorker).run\
\tgithub.com/pingcap/ticdc/cdc/sink/mysql.go:820\
github.com/pingcap/ticdc/cdc/sink.(*mysqlSink).createSinkWorkers.func1\
\tgithub.com/pingcap/ticdc/cdc/sink/mysql.go:640\
runtime.goexit\
\truntime/asm_amd64.s:1371"]